Question

Mike recently increased the size of his Jeep tires from the original 29 inch diameter to the larger 33.73 inch diameter. If Mike didn't recalibrate his speedometer, how fast is he really going on the new tires when his speedometer shows he is traveling 60 mph?

a. 54.5 mph
b. 62.1 mph
c. 66.1 mph
d. 69.8 mph

Answer 1

d. 69.8 mph

Explanation:

Since, the ratio of the diameter of the tyre of a vehicle and its speed must be constant,

Given,

The original diameter of the tyre = 29 inch,

Original speed = 60 mph,

Thus, the ratio of diameter and the speed of the vehicle =
`(29)/(60)`

New diameter of the tyre = 33.73 inch,

Let x be the new speed of the vehicle =
`(33.73)/(x)`

`\implies (29)/(60)=(33.73)/(x)`

`\implies x=(33.73* 60)/(29)=69.79\approx 69.8\text{ mph}`

Hence, the actual speed of the vehicle would be 69.8 mph.

OPTION D is correct.